In electrolyzers equipped with a cathode used for chlor-alkali electrolysis, usually, three components: an anode, an ion exchange membrane and a hydrogen generating cathode are arranged in close contact with each other to achieve decreased electrolysis voltage. However, in large electrolyzers having an electrolysis area as much as a few square meters, when accommodating an anode and a cathode as rigid members in an electrode chamber, it has been difficult to keep both electrodes in close contact with the ion exchange membrane and maintain an inter-electrode distance at a predetermined value.
Conventionally, as a method for closely contacting the three components: anode-ion exchange membrane-cathode with each other, there has been employed a method in which the pressure inside a cathode chamber is set higher than that inside an anode chamber to uniformly contact an ion exchange membrane with the anode, and then, a non-rigid material such as woven fabric, non-woven fabric or a net of thin metal wires, or a rigid material such as a leaf spring is arranged on a current collector on the back of the cathode to use its reaction force for close contact with the ion exchange membrane.
However, such a conventional non-rigid material has had drawbacks in that, when excessively pressed from the anode side after being installed into an electrolyzer, the non-rigid material is partially deformed and thereby causes the inter-electrode distance to be nonuniform or causes the thin wires to stab into the ion exchange membrane. In addition, rigid materials such as a leaf spring have had drawbacks in that they damage the ion exchange membrane or their reuse become impossible due to plastic deformation produced therein.
Thus, in Patent Document 1, there has been reported an electrolyzer in which, instead of such conventional materials, a metal coiled body was installed between a cathode and a cathode end plate to uniformly press the cathode in a diaphragm direction so as to keep respective members in close contact with each other. In the electrolyzer described in Patent Document 1, however, whereas the electrolyzer can be stably operated keeping the respective members in sufficiently close contact with each other because of an extremely small wire diameter of the metal coiled body and a high deformation rate thereof, there have been drawbacks in that the number of components increases due to installation of the metal coiled body in addition to the anode or the cathode in the electrolyzer and contact may become insufficient in case of a rigid cathode.
Accordingly, furthermore, Patent Document 2 has reported an electrolytic electrode in which, instead of using a metal coiled body to press an electrode in an ion exchange membrane direction, an elastic cushion member supporting an electrode catalyst formed by twisting a metal coiled body around an anticorrosive frame is applied to the electrode, and an electrolyzer using the same. The above electrolytic electrode maintains its configuration for a long period of time due to its high strength and toughness, it does not cause mechanical damage to the ion exchange membrane or the like and does not produce excessive deformation leading to insufficient power supply, so that stable operation can be continued for a long term. Moreover, the electrolyzer accommodating this electrode ensures the electrical connection between the electrode and an electrode current collector, thus allowing secure power supply.